Research by Kiwi scientists has revealed how chemotherapy stimulates the release of tiny bubbles from the surface of cancer cells that cause potentially fatal blood clots.

While most deaths from cancer are caused by uncontrolled growth of the tumour in vital organs, the second most common cause of cancer-related deaths involves blood clotting resulting in thrombosis, such as pulmonary embolisms.

This causes blockage of major blood vessels, preventing oxygen and nutrients from reaching vital organs.

Although often life-saving and life-prolonging, chemotherapy is associated with a six- to sevenfold increase in the risk of thrombosis in cancer patients.


The link between cancer and thrombosis was noted more than 100 years ago, but the reasons for the association have been elusive.

But now, a team of Otago University researchers have discovered cancer cells treated with chemotherapy release lipid-rich bubbles from their membranes that activate coagulation, or clotting, processes.

"We now have insight into how these bubbles from dying cancer cells may cause thrombosis during chemotherapy," said Associate Professor Alex McLellan, who led the team.

The research has demonstrated that certain solid cancers are more active in promoting blood coagulation, as compared to lymphomas.

"A general pattern is that cancers such as pancreatic, lung and brain cancers carry the largest risk of thrombotic events."

Since cancer-induced, clotting events also encouraged tumour progression, the work opened up the possibility of developing inhibitors to the major coagulation pathway identified in cancer cells.

Associate Professor Alex McLellan
Associate Professor Alex McLellan

"The coagulation factors identified may be the Achilles heel of the cancer," he said.

"Our current work is exploiting these molecules as targets for cellular and drug-based therapies."


Another Otago University study has shown that some chemotherapy agents produce unfavourable changes to blood lipids in breast cancer patients, which may increase the risk of cardiovascular disease.

But McLellan and one of that study's co-authors, Professor Sally McCormick, were quick to point out that the benefits of chemotherapy far outweigh possible risks of cardiovascular diseases and thrombosis.

"However, while chemotherapy can be life-saving, it does carry some risks," they say.

"A new challenge is being able to identify those patients most at risk and providing effective management to mitigate this risk."